A light-emitting diode is a type of semiconductor device. Development of LEDs has been vigorous due to its many advantages, including its small size, luminesence, short reaction time, long life time, and low power consumption.
Generally, LED chips can be classified into two main categories: those with lateral structures and those with vertical structures. With lateral structures, the two electrodes of an LED chip are located on the same side of the LED chip. With vertical structures, the two electrodes of an LED chip are located on opposite sides of the LED chip. LEDs having a vertical structure can improve upon issues of current spreading, which occurs in LEDs having a lateral structure. LEDs with a vertical structure have better performance in current spreading, thermal cooling, and emission efficiency, and may solve the problem of light shielding caused by the electrodes, and thus increase the emission area of LEDs. Therefore, LEDs having a vertical structure have drawn more and more attention from researchers. The vertical structure is expected to become the main LED chip structure in the future, especially for application in the field of general lighting.
Although existing LED manufacturing processes have generally been adequate for their intended purposes, they have not been entirely satisfactory in all respects. There are still many aspects of existing LED manufacturing processes that need to be improved.